Critical Islands

TL;DR

This paper proposes a holographic method to identify quantum islands in braneworld black holes, potentially resolving information paradox issues by analyzing Ryu-Takayanagi surfaces in specific AdS geometries.

Contribution

It introduces a new prescription for locating quantum islands in braneworld black holes using holography, applicable to critical Randall-Sundrum models with massless gravitons.

Findings

Identification of conditions for quantum islands in braneworld black holes.

Verification of the approach in a 3D toy model with an analytic black funnel.

Evidence suggesting resolution of the information paradox in these systems.

Abstract

We discuss a doubly-holographic prescription for black holes in braneworlds with a vanishing cosmological constant. It involves calculating Ryu-Takayanagi surfaces in AdS black funnel spacetimes attached to braneworld black holes in the $ critical$ Randall-Sundrum II model. Critical braneworlds have the virtue of having massless gravitons. Our approach should be useful when the braneworld is a cosmological black hole interacting with deconfined, large-$N$ matter. In higher dimensions, explicit funnel metrics will have to be constructed numerically -- but based on the general structure of the geometry, we present a natural guess for where one might find the semi-classical island. In a 3-dimensional example where a toy analytic black funnel is known, we can check our guess by direct calculation. We argue that this resolves a version of the information paradox in these braneworld systems, by finding strong evidence for "cosmological islands". Comoving Ryu-Takayanagi surfaces and associated UV cut-offs on the brane, play natural roles.